One proposed structure of a slip detection apparatus is mounted on a vehicle, which is driven with power of a driveshaft output to left and right front wheels as drive wheels. The slip detection apparatus of the proposed structure includes wheel speed sensors and a rotational position sensor detecting the rotational position of the driveshaft (see, for example, Patent Document 1). This prior art slip detection apparatus compares an angular acceleration of the driveshaft calculated from the rotational position detected by the rotational position sensor with a predetermined threshold value and detects the occurrence of a slip of the drive wheels based on the result of the comparison. The occurrence of the slip of the left and right front wheels is detected based on whether a difference between left and right wheel speeds measured by the wheel speed sensors respectively attached to the left and right front wheels exceeds a preset allowable range about an estimated difference between the left and right wheel speeds in the grip condition.
Patent Document 1: Japanese Patent Laid-Open No. 2005-47313